This section provides background information related to the present disclosure which is not necessarily prior art.
Natural gas fueled engines are gaining popularity as an environmentally friendly alternative to petroleum based fuels such as gasoline and diesel fuel. Natural gas is generally regarded as being better for the environment because engines running on natural gas generally have reduced emissions and natural gas is more abundant than petroleum.
Natural gas is a naturally occurring hydrocarbon mixture containing primarily methane. The methane content significantly contributes to the combustion characteristics of natural gas and hence its quality. However, natural gas also contains smaller percentages of other hydrocarbons, carbon dioxide, nitrogen, water vapor, and hydrogen sulfide. The composition of natural gas varies widely depending on the geographic origin of the natural gas and the amount of time that has passed since it was extracted. The composition of natural gas also varies depending on whether the natural gas comes from a well head, a landfill, or other bio-mass derivatives. As a result, natural gas has widely varying combustion characteristics.
In addition to its use as a fuel to power engines, natural gas is widely used for residential and commercial heating, cooking, and power generation. In the residential and commercial industry setting, methods and equipment have been developed for measuring the caloric value of natural gas and its flammability limits due to the wide variances in composition. However, developments allowing for real-time quality determination of the natural gas being injected into engines have been slow to materialize.
Natural gas can have widely varying energy content and knock resistance properties depending on the concentration of various components in the fuel. These variations can have a severe impact on the operation of natural gas fueled engines and can cause high degrees of cyclic combustion variability, mis-fire, low performance, and engine knock. These are unwanted operating conditions which can degrade the performance, reliability, and service life of natural-gas engines. What is needed is a system and method for determining the quality of natural gas as it flows through an engine's fuel system to enable the real-time adjustment of operating parameters of the engine.